The life and death of a cheeky and bright five-year-old boy from North Queensland is shaping world-leading research into a rare genetic disease.
Grayson Little had what is known as dyskeratosis congenita and a gene mutation that had never been seen before.
The discovery of the mutation has not only helped Grayson's parents have another healthy child but also another young mum with the same genetic disorder.
Rachel Little said right from Grayson's diagnosis, they were interested in being a part of studies to find a treatment and cure.
While a cure was not identified during Grayson's short lifetime, his family is hopeful for others.
Ms Little described her son's decline as gradual.
"He was already developmentally delayed but the things he could do just become a lot worst because of his lack of oxygen," she said.
"In the last few months he was basically bed-bound and he would just lay in bed or sit in his wheelchair.
"He was just too tired and exhausted."
Twenty-three-year-old mother Diandra Edmondson said without Grayson's research, she might not be here today.
"I didn't know what the future held until the genetic mutation was found," she said.
"The more time that passes [and] the more research that gets done, the more families get a better outcome."
A definitive diagnosis
DNA in human cells is bundled into 46 chromosomes.
The two ends of every chromosome are protected by structures called telomeres.
When the telomeres fail to provide proper protection, it can lead to a spectrum of health problems including bone marrow failure and the inability to make new blood cells.
Tracy Bryan from the Children's Medical Research Institute in Sydney said Grayson had inherited a mutation in each copy of his telomerase gene.
"We all have two copies of every gene, one inherited from mum and one from dad," she said.
"Unfortunately, both mum and dad in this case had a different mutation in the gene and Grayson was unlucky enough to inherit both of them.
"His telomerase was defective and not able to maintain his stem cells in his bone marrow, lungs, kidney and liver."
In his five years, Grayson had two bone marrow transplants.
"If patients with this disorder are treated in the normal way for a bone marrow transplant, which is to give the patient a dose of chemotherapy to get rid of their own cells before the donor cells are put in ... if that happens in these patients, it's extremely toxic," Professor Bryan said.
She said the research gave Grayson a definitive diagnosis.
"The family are amazing ... they realise the value of the research and they're very supportive of what we do.
"It was able to give them some certainty and help with family planning.
"They subsequently had a healthy baby boy who only has one of the mutations, not both.
"When Grayson passed away, I was devastated we couldn't do more for him."
Identifying mutations in others
Few people can grasp the power of medical research as well as Ms Edmonson.
"I was diagnosed with leukaemia, but I didn't have leukaemia," she said.
"My symptoms were severe bruising, bleeding and if I sort of cut myself or anything like that, just unusual bleeding that wouldn't stop as fast as it should.
"Throughout my schooling years, I was always trialling new drugs and new sorts of procedures to try and help my condition, but nothing really worked."
Continued testing revealed a different but equally concerning condition.
"I was eight years old when I was diagnosed with aplastic anaemia.
"Even the doctors were trying to figure exactly what was wrong and where it had stemmed from."
When Ms Edmonson was 17, she was told she had no choice but to have a bone marrow transplant.
It was when she was preparing for the transplant that Professor Bryan was able to diagnose her with dyskeratosis congenita ... and find the gene that had caused Ms Edmonson's condition.
"Thankfully it was found because if it wasn't, my treatment would have been a lot different," Ms Edmonson said.
"They did say to me I could have died if they hadn't known about that.
"[Grayson] or any other child in that situation is kind of like a guinea pig, because it's such a rare genetic or telomere syndrome."
Global impacts
Professor Bryan's findings have now been published in international databases.
"Clinicians around the world, wherever they are, if they find patients with the same mutations, they can look it up and they can give the patients in their family an answer straight away."
But there is still a lot more work to be done.
Professor Bryan said her team was working on what they hoped would be a promising avenue — gene therapy.
"This is where you take the cells out of the stem cells out of the bone marrow of the patient and you modify the genes in a culture dish.
"You fix the mutations essentially and then you put the patient's own cells back into their own bone marrow."
